我域名是有备案的 在控制台是有这条cdn记录的
~ curl -I www.zadz.cn
HTTP/1.1 503 Service Temporarily Unavailable
Server: Tengine
Content-Length: 0
Connection: keep-alive
Via: cache30.l2st3-2[0,503-274,M], cache5.l2st3-2[124,0], kunlun10.cn210[173,503-1281,M], kunlun8.cn210[312,174,0]
X-Swift-Error: forward retry timeout
Age: 0
X-Cache: MISS TCP_MISS dirn:-2:-2
X-Swift-SaveTime: Fri, 31 Aug 2018 02:52:19 GMT
X-Swift-CacheTime: 1
X-Swift-Error: orig response 5xx error
Timing-Allow-Origin: *
EagleId: 7519859c15356839388136537e
这是什么原因